CN113825654A

CN113825654A - Pneumatic tire

Info

Publication number: CN113825654A
Application number: CN201980096081.0A
Authority: CN
Inventors: 石原大雅; 渡边润; 山口卓; 加藤庆一; 向川友德; 牛头诚; 满田翔
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 2019-05-07
Filing date: 2019-11-25
Publication date: 2021-12-21
Also published as: EP3967524A1; JP2020183158A; JP7132172B2; US20220250421A1; WO2020225937A1; EP3967524A4

Abstract

The pneumatic tire is provided with a pair of bead cores embedded in a pair of bead portions, the pair of bead cores respectively including a pair of small bead cores divided in a tire widthwise direction; and further provided with a carcass comprising one or more carcass plies, the carcass being astride a pair of bead cores in a toroidal manner and comprising ends arranged and fixed between a pair of small bead cores. The muffler is disposed on the inner surface of the tire at the pair of bead portions.

Description

Pneumatic tire

Technical Field

The present disclosure relates to a pneumatic tire.

Background

In order to reduce the resonance vibration (cavity resonance) of air or gas generated in the tire inner cavity, it is known to arrange a silencer formed of a sponge material or the like on the tire inner surface (for example, patent document 1). The silencer can convert the vibration energy of air or gas in the inner cavity of the tire into heat energy, and cavity resonance in the inner cavity of the tire is reduced.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2005-254924

Disclosure of Invention

Problems to be solved by the invention

However, since heat is easily retained in the muffler formed of a sponge material or the like, an adhesive layer that bonds the inner surface of the tire and the muffler melts, causing the muffler to separate from the inner surface of the tire, leading out a thermal failure or the like of another tire member, and thus reducing the durability of the tire.

Accordingly, it is an object of the present disclosure to provide a pneumatic tire that allows for improved noise reduction performance without reducing tire durability.

Means for solving the problems

The related configuration of the present disclosure is as follows.

The pneumatic tire of the present disclosure includes:

a pair of bead cores embedded in a pair of bead portions, the pair of bead cores respectively including a pair of small bead cores divided in a tire width direction; and

a carcass including one or more carcass plies, the carcass being annularly spanned between the pair of small bead cores with ends of the carcass sandwiched between and engaged with the small bead cores, respectively, wherein

The noise damper is disposed on an inner surface of the tire in the pair of bead portions.

Here, the "bead portion" means a portion ranging from a rim base line (a line passing through the tip of the bead toe and parallel to the tire width direction as shown in the enlarged view of fig. 1) to the tire radial direction outer end of the small bead core of the plurality of small bead cores in which the tire radial direction outer end is located at the outermost side in the tire radial direction, in a region in the tire radial direction in a state where the tire is mounted on the applicable rim while being filled with a prescribed internal pressure and no load is applied.

Here, the "applicable rim" refers to a standard rim (measurement rim in ETRTO standard manual and design rim in TRA yearbook) of applicable sizes described or to be described in the future in an industrial standard effective in an area where a tire is manufactured and used (i.e., JATMA yearbook of japan automobile tire manufacturer association, standard manual of ETRTO (european tire and rim technical organization), yearbook of TRA (tire and rim association), etc.) in europe, in other words, the above-mentioned "rim" includes not only existing sizes but also sizes that may be included in the above-mentioned industrial standard in the future, and an example of the "size to be described in the future" may include a size described under the "future development" of the 2013 yearbook. Meanwhile, in the case of a dimension that is not described in the above-mentioned industrial standards, "rim" means a rim having a width corresponding to the bead width of the tire.

The "predetermined internal pressure" is an air pressure (maximum air pressure) corresponding to the maximum load capacity of the individual wheel in the applicable size and ply level according to JATMA or the like. In the case of dimensions not described in the above-mentioned industrial standards, "prescribed internal pressure" means an air pressure (maximum air pressure) corresponding to a prescribed maximum load capacity per vehicle to which a tire is to be mounted.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present disclosure, it is possible to provide a pneumatic tire that allows the noise reduction performance to be improved without reducing the durability of the tire.

Drawings

In the drawings:

fig. 1 is a cross-sectional view in the tire width direction of a pneumatic tire according to an embodiment of the present disclosure.

Detailed Description

Embodiments of the present disclosure will be described in detail below by way of examples with reference to the accompanying drawings.

Fig. 1 is a cross-sectional view in the tire width direction of a pneumatic tire (hereinafter also simply referred to as "tire") according to an embodiment of the present disclosure. Fig. 1 shows a cross section of a tire in the tire width direction in a state where the tire is mounted on an applicable rim while being filled with a prescribed internal pressure and no load is applied. As shown in fig. 1, the tire 1 includes a pair of bead portions 2 and a carcass 3. The tire 1 further includes, in order, a belt 4 and a tread 5 on the tire radial direction outer side of the crown portion of the carcass 3, and in the illustrated example, the belt 4 includes two belt layers 4a and 4 b.

As shown in fig. 1, the tire 1 includes a pair of bead cores 2a embedded in a pair of bead portions 2. As shown in fig. 1, the pair of bead cores 2a respectively include a pair of small bead cores 21, 22 (a small bead core 21 on the inner side in the tire width direction and a small bead core 22 on the outer side in the tire width direction) that are separated in the tire width direction. In this example, a single bead wire is wound around each small bead core 21, 22. In the illustrated example, the shapes of the small bead cores 21, 22 in cross section are respectively a single straight line; however, the present example is non-limiting and various cross-sectional shapes are acceptable. Further, for example, a metal such as steel may be used as the material of the bead core 2a or the like. In the illustrated example, an inner reinforcing rib 23 is disposed on the tire width direction inner side of the small bead core 21, and an outer reinforcing rib 24 is disposed on the tire width direction outer side of the small bead core 22, thereby improving the rigidity of each bead portion 2. In this example, the inner reinforcing bead 23 and the outer reinforcing bead 24 are formed of rubber.

In the example shown in fig. 1, the carcass 3 includes a carcass ply having a radial arrangement (the carcass cords are at an angle of 85 ° or more, preferably 90 ° with respect to the tire circumferential direction). However, in the present disclosure, the number of the carcass plies is not limited and may be two or more. In the present embodiment, the carcass 3 is annularly spanned between the pair of bead cores 2a with its end portions (end portions 3a in the present example) sandwiched between and engaged with the pair of small bead cores 21 and 22, respectively. In the present disclosure, the carcass 3 may be in the form of a bias carcass.

In the example shown in fig. 1, the tire 1 includes a belt 4 having two belt layers 4a and 4 b. In the present example, the belt layers 4a and 4b are in the form of inclined belt layers in which belt cords thereof are inclined with respect to the tire circumferential direction and cross each other between the layers across the tire equatorial plane CL. The number of the slant belt layers is not limited. The inclination angle of the belt cords of the belt layer is not limited, and may be, for example, in the range of 35 ° to 85 ° with respect to the tire circumferential direction. Further, one or more reinforcing belt layers may be arranged outside and/or inside in the tire radial direction of each of the slant belt layers. The reinforcing cords of the reinforcing belt layer are not limited and may extend at an angle of 0 ° to 5 ° with respect to the tire circumferential direction, for example. The respective widths of the belt layer and the reinforcing belt layer in the tire width direction are not limited. As the material of the belt cord and the reinforcing cord, a known material may be suitably used, and likewise, the number of the end portions and the like may be suitably set.

In the illustrated example, the tire 1 includes a tread 5 in the form of a tread rubber layer. However, in the present disclosure, the tread rubber providing the tread 5 may include a plurality of different rubber layers. In this case, a plurality of different rubber layers may be stacked in the tire radial direction and/or arranged side by side in the tire width direction.

In the present embodiment, as shown in fig. 1, a muffler 7 is disposed on an inner surface 6 of the tire 1 in each of the pair of bead portions 2. In the present embodiment, the muffler 7 is a porous body (sponge material in the present example). Although the shape of the muffler 7 is substantially a rectangular shape in a cross section in the tire width direction in this example, the shape of the muffler 7 is not limited. In addition, there is no limitation on the size and the like of the muffler 7, but the volume of the muffler 7 is preferably in the range of 0.1% to 80% of the total volume of the inner cavity of the tire 1. This is because the noise cancellation performance can be enhanced as long as the volume of the noise canceller 7 is 0.1% or more of the total volume of the inner cavity of the tire 1, and the increase in weight due to the noise canceller 7 can be reduced as long as the volume of the noise canceller 7 is 80% or less of the total volume of the inner cavity of the tire 1. The "volume of the noise damper" herein means a volume in a state where the tire 1 is removed from the rim at normal temperature and pressure. Further, the "total volume of the inner cavity of the tire" means the total volume determined when the tire 1 is mounted on an applicable rim while being filled with a prescribed internal pressure.

In the present example, the muffler 7 extends continuously in the tire circumferential direction, but may be formed discontinuously. Further, although in the present example, the muffler 7 is disposed on the inner surface 6 of the tire 1 only in each bead portion 2, the muffler 7 may be partially located on the inner surface 6 of the tire 1 in the sidewall portion. In this case, the muffler 7 is preferably continuous from each bead portion 2 to the sidewall portion.

The material of the muffler 7 that is only required to be controlled so as to allow the cavity resonance energy to be reduced due to the cavity resonance energy being released, absorbed, converted into another energy (e.g., thermal energy), or the like is not limited to the above-described porous body, and may be, for example, a nonwoven fabric of organic fibers or inorganic fibers.

In the case where the muffler 7 is a sponge material as in the present embodiment, the sponge material may be a sponge-like porous structure, for example, including a so-called sponge having interconnected cells (cells) formed by foaming rubber or synthetic resin. Further, the sponge material includes, in addition to the above-mentioned sponge, a mesh made by entangling and integrally connecting animal fibers, plant fibers, synthetic fibers, and the like. It should be noted that the above-mentioned "porous structure" is not limited to a structure having interconnected cells, but includes a structure having closed cells. The sponge material as described above has voids formed on the surface and inside thereof, which convert the vibration energy of the vibrating air into heat energy. This reduces cavity resonance in the tire inner cavity, and thus can reduce road noise.

Examples of the material of the sponge material include synthetic resin sponges such as ether-based polyurethane sponge, ester-based polyurethane sponge, polyethylene sponge, and rubber sponges such as chloroprene rubber sponge (CR sponge), ethylene propylene diene monomer sponge (EPDM sponge), and nitrile rubber sponge (NBR sponge). From the viewpoints of noise reduction, weight reduction, adjustability of foaming, durability, and the like, for example, a polyurethane sponge including an ether polyurethane sponge or a polyethylene sponge is preferably used.

In the case where the muffler 7 is a sponge material as in the present embodiment, the hardness of the sponge material is preferably, but not limited to, in the range of 5N to 450N. When the hardness is 5N or more, the noise reduction performance can be improved. When the hardness is 450N or less, the adhesiveness of the muffler can be improved. Likewise, the hardness of the silencer is preferably in the range of 8N to 300N. Here, "hardness" is a value measured according to method a of item 6.3 of the measurement methods of item 6 of JIS K6400.

Further, the specific gravity of the sponge material is preferably in the range of 0.001 to 0.090. This is because, in the case where the specific gravity of the sponge material is 0.001 or more, the noise reduction performance can be improved, and in the case where the specific gravity of the sponge material is 0.090 or less, the increase in weight due to the sponge material can be reduced. Likewise, the specific gravity of the sponge material is more preferably in the range of 0.003 to 0.080. Here, the "specific gravity" is a value obtained by converting the apparent density into a specific gravity according to the measurement method of item 5 of JIS K6400.

Further, the tensile strength of the sponge material is preferably in the range of 20kPa to 500 kPa. This is because the adhesiveness can be improved when the tensile strength is 20kPa or more, and the productivity of the sponge material can be improved when the tensile strength is 500kPa or less. Likewise, the tensile strength of the sponge material is more preferably in the range of 40kPa to 400 kPa. Here, the "tensile strength" is a value measured with a No. 1 dumbbell test piece according to the measurement method of item 10 of JIS K6400.

Further, the elongation at break of the sponge material is preferably in the range of 110% to 800%. This is because the generation of cracks in the sponge can be reduced when the elongation at break is 110% or more, and the productivity of the sponge can be improved when the elongation at break is 800% or less. Likewise, the elongation at break of the sponge material is preferably in the range of 130% to 750%. Here, "elongation at break" is a value measured with a No. 1 dumbbell test piece according to the measurement method of item 10 of JIS K6400.

Further, the tear strength of the sponge material is preferably in the range of 1N/cm to 130N/cm. This is because the occurrence of cracks in the sponge can be reduced when the tear strength is 1N/cm or more, and the productivity of the sponge can be improved when the tear strength is 130N/cm or less. Likewise, the tear strength of the sponge material is preferably in the range of 3N/cm to 115N/cm. Here, the "tear strength" is a value measured with test piece No. 1 according to item 11 of JIS K6400.

Further, the foaming ratio of the sponge material is preferably in the range of 1% to 40%. This is because the noise reduction performance can be improved when the expansion ratio is 1% or more, and the productivity of the sponge material can be improved when the expansion ratio is 40% or less. Likewise, the foaming ratio of the sponge material is preferably in the range of 2% to 25%. Here, the "foaming ratio" is a value obtained by subtracting 1 from a ratio a/B of a specific gravity a of a solid phase portion of the sponge material to a specific gravity B of the sponge material and multiplying the result by 100.

Furthermore, the total mass of the sponge material is preferably in the range of 5g to 800 g. This is because, in the case of a mass of 5g or more, the noise reduction performance can be improved, and in the case of a mass of 800g or less, the increase in weight attributed to the sponge material can be reduced. Likewise, the mass of the sponge material is preferably in the range of 20g to 600 g.

The action and effect of the pneumatic tire according to the present embodiment will be explained below.

First, in the tire 1 of the present embodiment, arranging the muffler 7 on the inner surface 6 of the tire 1 in each bead portion 2 makes it possible to enhance the noise reduction performance with reduced resonance vibration (cavity resonance).

Here, in the present embodiment, each end portion (end 3a in this example) of the carcass 3 is sandwiched between a pair of small bead cores 21 and 22. With this configuration, the end portion (end 3a in this example) of the carcass 3 is fixed, which makes it possible to reduce heat accumulation at the end portion (end 3a in this example) of the carcass 3. Further, the bead cores 2a each include a pair of small bead cores 21 and 22 separated, which reduces the volume of the bead core 2a as one of the heat accumulation sources. Therefore, the heat held in the muffler 7 can be reduced by a small amount of heat accumulation at each bead portion 2, which allows the separation of the muffler 7 from the inner surface 6 of the tire 1 to be reduced, so that it is less likely to cause thermal failure or the like of another tire member, and thus allows the tire durability to be prevented from being damaged.

Therefore, the pneumatic tire of the present embodiment is allowed to improve the noise reduction performance without reducing the durability of the tire.

Preferably, the tire of the present disclosure includes a tread portion and a sealant layer disposed on an inner surface of the tire in the tread portion. This is because, if the pneumatic tire has a puncture, the puncture can be repaired by the sealant layer. In particular, as in the above-described embodiment, in the case where the noise damper 7 is not arranged on the inner surface 6 of the tire 1 in the tread portion (but only on the inner surface 6 of the tire 1 in each bead portion 2), no sealant enters into the hole of the noise damper 7 such as a sponge material or the like, which allows the puncture repair function to be sufficiently exerted.

In the present disclosure, it is preferable that 50% or more of the volume of the muffler is arranged on the tire inner surface of each of the pair of bead portions. This is because the presence of 50% or more of the volume of the muffler in the above-described region makes it possible to improve the noise cancellation performance with higher reliability without reducing the durability of the tire. For the same reason, it is more preferable that 60% or more of the volume of the muffler is present in the region where each of the pair of bead portions in the tire radial direction is present, and it is further preferable that 70% or more of the volume of the muffler is present in the region where each of the pair of bead portions in the tire radial direction is present. From the viewpoint of preventing the reduction in tire durability, it is preferable that 100% of the volume of the muffler be present in the region where the pair of bead portions in the tire radial direction are located. However, in view of further improving the noise cancellation performance while ensuring the volume of the noise damper, it is preferable that 50% to 80% of the volume of the noise damper be present in the region where the pair of bead portions in the tire radial direction are located.

Description of the reference numerals

1 tire (pneumatic tire)

2 bead part

2a bead core

21. 22 small bead core

23 inner reinforcing rib

24 outside reinforcing bar

3 tyre body

3a carcass edge

4 belted

4a, 4b belt layer

5 Tread

6 inner surface of tyre

7 silencer

Claims

1. A pneumatic tire, comprising:

2. The pneumatic tire of claim 1, further comprising a tread portion, characterized in that

A sealant layer is disposed on the inner tire surface in the tread portion.

3. A pneumatic tire according to claim 1 or 2, wherein 50% or more of the volume of the noise damper is arranged on the tire inner surface in the pair of bead portions.